The invention relates to a beverage-making device which constitutes an improvement over the prior art, particularly directed to those devices which automatically brew coffee.
In such devices, a water supply line is in direct communication with an inlet valve for on-demand admittance of cold water to a water-heating container in which a constant source of hot water for brewing is available. The inlet valve is electrically operated to open for a pre-set brewing cycle equal to the amount of time required to provide sufficient liquid to fill a receiving decanter, such as a coffee pot.
A running thermostat senses the temperature in the water container and electrically communicates with a coiled, or looped, heating element so that the constant desired temperature is maintained.
Water systems for admitting cold water to the container include inlet tube means for dispensing the incoming water at the bottom of the container. As the cold water enters, displaced volumes of hot water at the top of the container are siphoned from the container to a brewing chamber, which is manually pre-filled with a load of fresh ground coffee. As incoming water reduces the water temperature in the container, the running thermostat senses this lower temperature and activates the heating element. The heating element remains energized until the thermostat senses that the required water temperature has been reached. With high capacity electric heating elements, a substantial temperature increase occurs over a short period of time. Should the running thermostat fail in the on position, a so-called "run away" condition will result whereby the heater will stay energized. Thereafter, the heating element will quickly evaporate the water and reach a dangerously high temperature. In order to prevent overheating, conventional systems include high limit thermostats. A high limit thermostat serves to de-activate the heating element when excessive temperatures are sensed. This safety feature is particularly useful when someone has inadvertently failed to fill the water container prior to initiating a brewing cycle. Without this feature the running thermostat would blindly sense the ambient air temperature inside the empty container. In response, the heating element would continue to operate until reaching a dangerous "red-hot" condition.
Customarily, the hot water container is provided with a hermetically sealed cover which supportively accomodates the aforesaid siphon, running and high limit thermostats, and inlet tube means, as well as the terminals for the heating element. A drawback to this typical arrangement is that only the temperature at the cover is sensed by the high limit thermostat. As a result, an excessively high temperature at lower portions of the container, localized near the heating element, can sometimes occur while the cover remains relatively cool. The remote disposition of a high limit thermostat at the container cover is inherently inefficient for detecting these temperature fluctuations at the bottom half of the container. A thermostat system which can immediately detect this dangerous condition, and promptly de-activate the heating element, would be a significant achievement.
Running thermostats are typically connected to an enlarged sensing bulb by means of a thin capillary tube. The bulb end is usually positioned at the lower half of the container. The capillary tube must therefore extend downwardly into the container to reach the bulb end. A long guide sleeve is used to hold the bulb in place. The guide sleeve is attached to the cover and extends downwardly into the container to surround and protect the capillary tube and the full length of the enlarged bulb end. Usually, guide sleeves are secured to the bottom of the heating coil so that the bulbs are fixed in the proper orientation. Deficiencies in this conventional arrangement have been encountered. Firstly, the enlarged bulb end is limited to only sensing temperatures in the vicinity of the bottom half or third of the container. Temperatures at the upper portions are not detected, and may in fact be sufficiently high to brew coffee without further activation of the heating coil. It would be considerably more advantageous to detect the mean temperature of the entire water volume. Secondly, conventional enlarged bulb thermostats have a temperature-sensing spread of about 6.degree.-8.degree. F. Thereby, the heating element is not quickly activated when the water becomes too cool and, once activated, will unnecessarily remain on for a period of time after the water has reached the desired temperature. A thermostat arrangement that reacts to smaller temperature changes would be economically beneficial, since the heater would be activated soon after the water falls below the usual brewing temperature of 205.degree. F. and then de-activated very shortly after this is attained.
The guide sleeve arrangements in the prior art have hindered maintenance procedures. In order to remove the thermostat and bulb for repair, the cover has had to be removed in order to disconnect the guide sleeve from the heating element. It would be a great aid to repair personnel to eliminate the need for a guide sleeve and provide a running thermostat, capillary tube and sensing tube that are completely disengageable from the device without requiring other components, such as the cover, to be disconnected or disturbed. A self-supporting sensing means would greatly advance the solution to this problem. Savings in maintenance time and repair costs would be made.
Automatic beverage-making devices have also included means for dispensing hot water for making tea, instant soup and the like. In the past these systems simply drained hot water directly from the water container. By extracting a volume of hot water from the container, the brewing capability of the device is diminished. Should a contemporaneous brewing cycle be desired, the container must first be re-filled with colder inlet water and then heated to elevate the temperature of the water to the necessary brewing level. The re-filling step has usually been initiated by the provision of a float switch arranged in the upper portion of the container which detects the drop in the water level. The inlet valve is electrically controlled by the switch which signals it to open until the float is satisfied. Due to lime build-up the switches can close and become inoperable. A hot water system that eliminates the need for a float switch would be a significant advance in the art. It would also be a valuable improvement to provide a hot water system which does not borrow from the water in the container but still makes hot water instantaneously available for these other purposes.
In order to distribute the siphoned hot water over the coffee grounds, typical beverage-making devices utilize resiliently biased spray means over which the siphoned water is directed. The spray means is usually a flat, perforate disk. Other devices have used a showerhead type arrangement wherein a siphon tube nozzle fluidly communicates with a spray means that is concave rather than disk-shaped. Spray means, in either form, provide for sprinkling hot water over the coffee grounds, which are disposed in the brewing basket, or chamber, therebelow. For effective brewing to take place, a "lazy" drip from the spray means is preferred for a uniform distribution of hot water over the ground coffee. A common problem, particularly with flat spray disks, has been that the siphoned water is too forcefully emitted in streams through a series of disk orifices which create an equal number of holes bored into the mound of coffee grounds. Quite oppositely, the desired drip phenomenon is an even flow over the grounds. It would therefore be of great value to provide a moderately paced gravity drip system which eliminates individual spray streams through the disk orifices onto the ground coffee. Spray disks also require cleaning due to the accumulation of lime deposits and other sediments found in water lines. As a result, the disks need to be removed for cleaning. The usual resilient connections between spray disks and associated mounting collars render the disks removable, but are inadequate for achieving a tight engagement therebetween. A tight seal between the periphery of the spray disk and mounting collar is highly desirable so that the siphoned hot water will not leak around the edges of the disk, but will be emitted only through the orifices.
Accordingly, a more effective interconnection between a spray disk and mounting collar would be a significant improvement over the foregoing devices. A positively locking connection would avoid the disadvantages of the resilient connections found in the prior art. It would also be beneficial to provide a tight sealed engagement that also snugly lodges a flexible gasket between the outer edge of the disk and the collar. Thereby, edge leakage would be prevented and a random drip pattern attained for the preferred even distribution of hot water over the coffee grounds.
For standard size automatic beverage-making devices, the hot water container normally holds at least three times the volume of a conventional coffee pot and usually takes the form of cylinder having a greater height than width. Cleaning these relatively large containers is necessary for taste and sanitary reasons. In order to remove sedimenations, such as lime deposits, the prevailing technique involves operating the beverage-making device for several cycles with a de-liming solution pumped through the container. Often, sediments at the container bottom are not dissolved and must be manually removed. In a more rudimentary cleaning method, the container is simply tipped over to empty the water. The latter is clearly an awkward and undesirable technique. A bottom drain, which allows the container to be fully emptied, would be preferable. Prior art devices have failed to provide a separate bottom draining system, probably due to the problems encountered with attaching drain tubes. The customary manner of affixing drains to metal containers is by welding. A disadvantage to such fittings is that the welds corrode and result in leakage. Welding also creates a fixed drain connection which impedes removing the container for repair and otherwise generally limits access to other components inside the device. It would accordingly be of significant value to provide a non-welded bottom drain system which avoids corrosion and leakage problems. In addition, it would be advantageous for the drain system to be disengageable to permit easy access to the interior of the device for the repair, or replacement, of mechanical and electrical components.
The present invention offers an improvement for beverage-making devices of the type described, which satisfies the needs set forth above. The invention may be briefly summarized as comprising, in part, a safety thermostat arranged with the container generally near the heater, which facilitates the prompt detection of excessive temperatures long before the cover becomes overheated. Thereby, a temperature increase can be immediately sensed in order to de-activate the heating element prior to reaching a dangerous condition.
An improved running thermostat system is provided, which senses the mean temperature of the entire volume of water and has a more precise temperature-sensing spread than found with previous devices. The thermostat communicates with the water by means of a self-supporting elongate sensing tube that extends for substantially the full height of the container and is connected to the thermostat by means of a capillary tube disposed outwardly of the cover. The unique thermostat and sensing tube arrangement is independently removable from the beverage-making device without disturbing the container cover or any other components.
The improvement further includes a tap-off hot water system which communicates with the incoming water supply upstream of the inlet control valve. The tapped-off water is directed into a water coil system arranged inside the container whereby the surrounding brewing water serves to heat the tapped-off water. When needed, the hot water is directed to flow through the coil to a hot water faucet located at the exterior of the device. The volume of hot water available for brewing coffee is therefore not reduced.
Also, an improved spray disk assembly forms part of the invention. The asembly eliminates resilient attachment and instead securely, but removably, locks a spray disk to a mounting collar above the brewing chamber. The disk is easily removed with a simple twisting motion without the need for tools. The improved spray disk assembly includes a sealing gasket which is tightly held against the mounting collar so that leakage around the periphery of the disk is eliminated. A series of orifices extend through the disk but a direct spray through each is avoided, and a random "slow-drip" for effective brewing is obtained.
A unique container draining system is additionally provided which associates with an aperture at the bottom of the hot water container. The system includes a flanged drain fitting partly arranged interiorly of the container and partly extending through the aperture to be threadengaged with an elbow and coupling assembly in a tightly sealed connection. A conventional valve is connected to the coupling means and is manually operable to facilitate emptying the water container. The system eliminates the problems with welding and affords quick disengagement from the container to allow easy access to the interior of the device.